CVE-2026-4666: The wpForo Forum plugin for WordPress is vulnerable to unauthorized modification of data due to the use of `extract($args, EXTR_OVERWRITE)` on user-co...

Description

The wpForo Forum plugin for WordPress is vulnerable to unauthorized modification of data due to the use of `extract($args, EXTR_OVERWRITE)` on user-controlled input in the `edit()` method of `classes/Posts.php` in all versions up to, and including, 2.4.16. The `post_edit` action handler in `Actions.php` passes `$_REQUEST['post']` directly to `Posts::edit()`, which calls `extract($args, EXTR_OVERWRITE)`. An attacker can inject `post[guestposting]=1` to overwrite the local `$guestposting` variable, causing the entire permission check block to be skipped. The nonce check uses a hardcoded `wpforo_verify_form` action shared across all 8 forum templates, so any user who can view any forum page obtains a valid nonce. This makes it possible for authenticated attackers, with Subscriber-level access and above, to edit the title, body, name, and email fields of any forum post, including posts in private forums, admin posts, and moderator posts. Content passes through `wpforo_kses()` which strips JavaScript but allows rich HTML.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.33%

24.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

References

Timeline

Published: Apr 17, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-4666?

The wpForo Forum plugin for WordPress is vulnerable to unauthorized modification of data due to the use of `extract($args, EXTR_OVERWRITE)` on user-controlled input in the `edit()` method of `classes/Posts.php` in all versions up to, and including, 2.4.16. The `post_edit` action handler in `Actions.php` passes `$_REQUEST['post']` directly to `Posts::edit()`, which calls `extract($args, EXTR_OVERWRITE)`. An attacker can inject `post[guestposting]=1` to overwrite the local `$guestposting` variable, causing the entire permission check block to be skipped. The nonce check uses a hardcoded `wpforo_verify_form` action shared across all 8 forum templates, so any user who can view any forum page obtains a valid nonce. This makes it possible for authenticated attackers, with Subscriber-level access and above, to edit the title, body, name, and email fields of any forum post, including posts in private forums, admin posts, and moderator posts. Content passes through `wpforo_kses()` which strips JavaScript but allows rich HTML.

How severe is CVE-2026-4666?

CVE-2026-4666 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.33% probability of exploitation in the next 30 days.

How do I fix CVE-2026-4666?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.